The German endured a miserable 2017, slipping from world number one to outside the top 20, but she has been revitalised at the start of this season and is yet to lose a match.

Sharapova, still unseeded after returning from her 15-month doping ban, sees matches against the leading players as the best way to test her level.

She said: "I came back with no ranking. I’m around 50 in the world at this point, so I know I’m going to be facing seeded players, first, second, third round. She happens to be the next one that I have to play.

"I look forward to these matches. I want to be playing against opponents that are former grand slam champions. She’s had success playing out here in these conditions on these courts. I want to see whether I am on that level."

Sharapova certainly seems to be enjoying returning to Australia for the first time since her failed doping test two years ago.

Her second-round win was a hugely satisfying one, with the Russian overcoming 14th seed Anastasija Sevastova, who had beaten her at the US Open, 6-1 7-6 (7/4).

"I love being in the city," said Sharapova. "I love Australia. I love the summer-time. I was watching this tournament last year with a box of Kleenex next to me sick. I feel like I transported myself into the TV this year and I’m finding myself on Rod Laver Arena competing. There’s a lot of things to smile about."

Kerber and Sharapova have played seven times before, with the Russian leading 4-3 but having lost the last two.

Kerber, who defeated Donna Vekic 6-4 6-1, said: "We both played in the past a lot of good matches. I know that I have to play my best tennis again. I think it will be a good match. She played very good the last two here."

Wimbledon champion Garbine Muguruza was the latest big name to tumble out of the tournament, the Spaniard losing 7-6 (7/1) 6-4 to world number 88 Hsieh Su-wei of Chinese Taipei.

Muguruza was the ninth of the top 16 seeds to exit before the end of the second round, emphasising the wide open nature of the women’s draw.

The third seed was philosophical afterwards, saying: "She’s definitely a very tricky opponent, and even more if she plays well. I think today she played well. I maybe could have done things better but, at the end, she deserves to win. That’s really it."

Eighth seed Caroline Garcia survived a tense clash with teenager Marketa Vondrousova, winning 6-7 (3/7) 6-2 8-6, but ninth seed Johanna Konta fell to lucky loser Bernarda Pera.

Karolina Pliskova and Madison Keys ensured they had no problems with the oppressive heat. Sixth seed Pliskova defeated Beatriz Haddad Maia 6-1 6-1 while US Open finalist Keys was even more emphatic in a 6-0 6-1 win over Ekaterina Alexandrova.

PA